Urinalysis - The Kidneys & Urine Formation

Question 1

What is the functional unit of the kidney?

Answer 1

nephron

Question 2

What does the nephron consist of?

Answer 2

-glomerulus
-Bowman’s capsule
-proximal convoluted tubule
-loop of Henle
-distal convoluted tubule

Question 3

What are the main constituents of urine?

Answer 3

-water
-urea (50%)
-sodium
-chloride

Question 4

What is urea?

Answer 4

the breakdown product of protein

Question 5

What is the main function of the glomerulus?

Answer 5

to filter blood

Question 6

What are the 3 renal functions associated with urine formation?

Answer 6

1. filtration - takes place in the glomerulus
2. reabsorption - renal tubules
3. secretion - renal tubules

Question 7

During urine formation, which substances are NOT allowed to filter through the glomerulus in significant amounts?

Answer 7

protein and cells

Question 8

Where does water reabsorption take place in the nephron?

Answer 8

proximal and distal tubules

Question 9

Where does reabsorption of glucose take place in the nephron?

Answer 9

proximal tubules

Question 10

Which hormone controls reabsorption of water in the distal tubules?

Answer 10

anti-diuretic hormone (ADH)

Question 11

Where is anti-diuretic hormone produced, stored, and secreted?

Answer 11

it is produced in the hypothalamus and stored and secreted by the posterior pituitary

Question 12

Which hormone controls reabsorption of sodium?

Answer 12

aldosterone

Question 13

Where is aldosterone produced?

Answer 13

adrenal cortex

Question 14

What is reabsorption of sodium linked to?

Answer 14

excretion of potassium (K+) and hydrogen ions (H+)

Question 15

What is the process by which filtered water, ions, and molecules leave the tubules for return to the blood via the peritubular capillaries?

Answer 15

reabsorption

Question 16

What is the process by which a substance from the blood is transported across the wall of the tubule into the filtrate?

Answer 16

secretion

Question 17

What is the glomerular filtration rate?

Answer 17

115-125 mL of filtrate formed per minute by the glomeruli

Question 18

How much of the filtrate will the renal tubules reabsorb?

Answer 18

All but 1 mL of the filtrate, which will be passed in the urine

Question 19

What is the renal threshold for glucose?

Answer 19

160-180 mg/dL

Question 20

What does the proximal convoluted tubule reabsorb?

Answer 20

-water
-sodium
-chloride
-potassium
-urea
-glucose
-amino acids

Question 21

What does the proximal convoluted tubule secrete?

Answer 21

hydrogen ions and medications

Question 22

What does the descending limb of the Loop of Henle reabsorb?

Answer 22

water

Question 23

What does the ascending limb of the Loop of Henle reabsorb?

Answer 23

sodium and chloride

Question 24

What does the distal convoluted tubule reabsorb?

Answer 24

sodium

Question 25

What does the distal convoluted tubule secrete?

Answer 25

hydrogen ions and potassium

Question 26

What is the final site for water reabsorption to make urine more dilute or concentrated?

Answer 26

the collecting duct

Question 27

What controls sodium and chloride reabsorption in the collecting duct?

Answer 27

aldosterone

Question 28

In the collecting duct, how is water reabsorbed?

Answer 28

by osmosis and in response to ADH

Question 29

Describe the renin-angiotensin-aldosterone axis.

Answer 29

-renin is secreted by the juxtaglomerular apparatus of the kidneys and catalyzes the conversion of angiotensin to angiotensin I
-angiotensin I stimulates the production of angiotensin II
-angiotensin II regulates renal blood by (1) constriction of renal arterioles and (2) secretion of aldosterone from the adrenal glands to facilitate retention of sodium

Question 30

What is the function of parathyroid hormone in urine formation?

Answer 30

promotes calcium reabsorption from the filtrate into the blood and excretion of phosphate ions from the blood into the filtrate

Question 31

Where is erythropoietin produced?

Answer 31

in the kidneys by the peritubular fibroblasts

-it stimulates RBC production in response to lowered oxygen levels